Alcatel OneTouch Star 6010D User Manual page 41

Touch to mute the current call. Touch this icon again to
unmute the call.
Touch to activate the speaker during the current call. Touch
this icon again to deactivate the speaker.
To avoid misoperation on touchscreen during a call, the screen
will be locked automatically when you put the cellphone close to
your ear; and it will be unlocked when the cellphone is taken
away from your ear.
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